Innate immune regulation during hepatitis C virus infection

描述(申请人提供)：丙型肝炎病毒(丙型肝炎病毒)是导致肝脏疾病和肝癌的主要原因。全世界有近1.7亿人慢性感染丙型肝炎病毒，目前的治疗方案只对一半的感染者有效。丙型肝炎病毒的持久性是由病毒逃避宿主天然免疫反应的能力所介导的。虽然宿主细胞胞液受体RIG-I感觉到丙型肝炎病毒RNA是外源的，但这种检测诱导的下游信号被RIG-I信号适配器-MAV的丙型肝炎病毒NS3/4A蛋白酶切割抑制。MAVS定位于线粒体和过氧化酶体，最近我发现它也定位于线粒体相关的内质网膜(MAM)，在RIG-I激活过程中，MAM将线粒体和过氧化酶体连接在一起形成突触。此外，我还发现，丙型肝炎病毒NS3/4A蛋白水解酶通过蛋白酶复合体的NS4A亚单位来靶向这些位置，以切割MAM上的MAV，而不是线粒体。这一数据强烈暗示MAV具有MAM定位，是驱动对丙型肝炎病毒的先天免疫反应的信号活性分子。这一建议将探索这样的假设，即在RIG-I途径激活期间靶向MAM的分子通过生化和蛋白质组学研究确定在宿主先天性免疫反应中招募的MAM分子，从而诱导MAVS信号复合体的形成。此外，NS4A靶向NS3/4A蛋白酶复合体到MAM的时空调节，以实现MAV的切割和免疫逃避，将通过识别指导这一靶向的宿主细胞因子和病毒成分来确定。这些研究将为激活NS3/4A在丙型肝炎病毒复制中的作用和先天免疫控制之间的转换的机制提供有价值的见解。此外，它们将成为研究的基础，以了解NS3/4A以MAM为靶点的MAV如何支持持续的丙型肝炎病毒感染。这些研究将确定MAM如何组织先天免疫信号和丙型肝炎病毒先天免疫逃避计划。对这些过程的详细了解将对治疗和疫苗设计策略产生影响，以限制由RIG-I途径感知的丙型肝炎病毒和其他RNA病毒的感染。

DESCRIPTION (provided by applicant): Hepatitis C virus (HCV) is a leading cause of liver disease and liver cancer. Nearly 170 million worldwide are chronically infected with HCV, and current treatment options are effective for only half of the infected. HCV persistence is mediated by the ability of the virus to evade the host innate immune response. While HCV RNA is sensed as foreign by the host cell cytosolic receptor RIG-I, the downstream signaling induced by this detection is suppressed by HCV NS3/4A protease cleavage of MAVS, the RIG-I signaling adaptor. MAVS is localized to mitochondria and peroxisomes, and I have recently found that it is also localized to mitochondrial- associated ER membranes (MAM), which link mitochondria and peroxisomes together into synapses during RIG-I activation. Further, I have found that the HCV NS3/4A protease targets these sites via the NS4A subunit of the protease complex for cleavage of MAVS on the MAM, and not the mitochondria. This data strongly implicates MAVS with MAM localization as the signaling active molecule that drives the innate immune response towards HCV. This proposal will explore the hypothesis that molecules targeted to the MAM during RIG-I pathway activation induce the formation of a MAVS signaling complex by using biochemical and proteomic studies that identify MAM-recruited molecules during the host innate immune response. In addition, the spatial-temporal regulation of NS4A targeting of the NS3/4A protease complex to the MAM for MAVS cleavage and immune evasion will be determined by identifying both the host cell factors and viral components that guide this targeting. These studies will provide valuable insights into the mechanism that activates the switch between the role of NS3/4A in HCV replication and innate immune control. Moreover, they will form the basis for studies to understand how MAM-targeting of MAVS by NS3/4A supports persistent HCV infection. These studies will determine how the MAM organizes both innate immune signaling and the HCV innate immune evasion program. A detailed understanding of these processes will have implications for therapeutic and vaccine design strategies to limit infection by HCV and other RNA viruses that are sensed by the RIG-I pathway.